Pneumatic pressure responsive actuator



NOV. 23, 1954 J, SLOAN 2,695,009

PNEUMATIC PRESSURE RESPONSIVE ACTUATOR Filed May 15, 1953 3 Sheets-Sheet l /ZZ AIRSUPPLX /Z/ /Z 9 E v i :o /06 W]:

IN VENTOR ZZ'JSZoan Nov. 23, 1954 F. .1. SLOAN 2,695,009

PNEUMATIC PRESSURE RESPONSIVE ACTUATOR Filed May 13, 1955 5 Sheets-Sheet 2 F. J. SLOAN PNEUMATIC PRESSURE RESPONSIVE ACTUATOR Nov. 23, 1954 Filed May 15, 1953 3 Sheets-Sheet 5 INVENTOR w w M w 9 h m M 7 9 a W? Z MNJQJ m H l w H a 6 A 7 w 5 FQW/ W P; 8/ w 4 V W Q 5 7 4 z a a a J a0 5 5 Z is w z m a u z z z x w YSUEII I i United States Patent 2,695,009 Patented Nov. 23, 1954 ice PNEUMATICPRESSURE RESPONSIVE ACTUATOR Frederick J. Sloan, Charleston, W. Va.

Application May 13, 1953, Serial No. 354,854

8 Claims. (Cl. 121-38) This invention relates to. a novel pneumatic. pressure responsive actuator. primarily intended to operate by air pressure the wheel brake, of a vehicle such as a. heavy truck, tractor, tractor trailer or bus, but which may be utilized for numerous other purposes.

One primary object of the present invention is to. pro.- vide av pneumatic pressure responsive actuator including a novel multiple valve structurev forming. a part thereof and which will eifectively function to. maintain the actuator operative even though a leak, may occur therein, and which would normally release the actuator.

Another object of the invention is to provide an actuator having novel means whereby a limited amount of air pressure will be maintained in a part thereof which is. insufficient to accomplish a movement of the actuator toward an operative position yet which will materially reduce the amount of compressed air required to render the actuator operative.

Another object of the invention is to provide a pneumatic pressure responsive actuator wherein the multiple valve additionally functions as a relief valve to admit air to the. actuator from the atmosphere should a partial vacuum occur in a part of the actuator.

Various other objects. and advantages of the invention will hereinafter become more fully apparent from the following description of the drawings, illustrating a. presently preferred embodiment thereof, and wherein:

Figure 1 is a fragmentary plan view showing the actuator applied to a portion of a motor vehicle for actuating a wheel brake thereof;

Figure, 2 is an enlarged, end elevational view, partly in section, looking toward the left hand end of, the actuator unit as seen in Figure 1;

Figure 3 is an enlarged central sectional view taken longitudinally through one end of the unit along a plane as indicated by the lines 3-3 of Figures 1 and 2;

Figure 3A is a similar view, partly in side elevation, showing the other end of said unit, taken substantially along a plane as indicated by the line 3A-3A of Figure l and on an enlarged scale;

Figure 4 is a longitudinal central sectional view of the multiple valve;

Figure 5- is a fragmentary side elevational view oi a forward end of the assembly on an enlarged scale, taken substantially along a plane as. indicated by the line 5,5 of- Figure, 1, and

Figure. 6 is a fragmentary front elevational view of a portion of one, part, of the diaphragm casing.

Referring more specifically to the drawings, the pneumatic pressure responsive actuator in its entirety is designated generally 8 and has been illustrated in the drawings in conjunction with a vehicle wheel brake, for applying the brake. However, as. the description proceeds it will become readily apparent that the actuator 8 has numerous other uses and may be employed for substantially any purpose where it is desirable to convert pneumatic pressure, to, a mechanical force, which may be transmitted by a thrust. It will also be understood that when employed as. a vehicle brake actuator that each wheel brake of a vehicle-will be equipped with one of the actuating units 8, only one oi whi h has be n ill strated.

The, unit 8 includes a diaphragm casing, designated generally 9 including a front section 1.9, a rear section It and an interme iate section 1 Supp t rms r brackets 13 are secured to and extendforwardly from he. trout. ca ing s c ion 1. an re ita ly secured at their forward ends to a vehicle axle housing 14 or may be secured to any other suitable support or part of a vehicle or other structure on which the unit 8 is mounted.

The casing end sections 10 and 11 are outwardly bowed relatively to one another and the intermediate section 12 constitutes a relatively wide ring member interposed between peripheral portions of the end sections it) and 11 and secured thereto by screw fastenings 15. Two flexible diaphragms 16 and 17' are disposed in the casing 9. The marginal portion of the auxiliary diaphragm 16 is clamped by certain of the fastenings between the peripheral portion of the end section 11 and the adjacent edge of the intermediate section 12 and the marginal portion of the main diaphragm 17 is similarly clamped between the other side edge of the intermediate section 12 and the peripheral portion of the end section 10.

An inlet fitting 18 has an outlet nipple. l9 detachably connected to a boss 20 of the end section it and in communication with a chamber 21 of the casing 9, formed by the end section 11 and diaphragm 16. The fitting 13 is provided. with a second outlet port 22 to which one end of a conduit 23 is connected. The inlet fitting 18 includes a hose nipple 24 the inlet passage or bore 25 of which communicates with the outlet nipple passage 19 and with the second outlet 22.

The other end of the conduit 23 connects with an angular conduit 26 at one end of said conduit 26, and the opposite end of the conduit 26 is dctachably connected to an end 27 of a multiple valve housing 28.

The valve housing 28 adjacent said end 27 is recessed to receive a main valve seat 29, preferably formed of a compressible sealing material, and a passage 30 extendsthrough said valve seat 29 and through a portion of the housing 28 and is in communication with the bore of the conduit 26. The housing 28 has a longitudinally extending bore 31 one end of which is in communication with the other end of the passage 30 and the opposite end of which opens outwardly of the other end 32 of the housing 28. An elongated main valve 33 extends from end-to-cnd' through the bore 31 and is slidably disposed therein and has a recessed end 34 which seats against the valve seat 29. The opposite end of the valve 33 is disposed beyond the housing end 32 and is. enlarged to form a head 35.

Said housing end 32 has an annular outwardly extending flange 36 which is flared away from said end 32 and forms one-half or section of a diaphragm casing 37 in conjunction with said end 32. The other section 38 of the diaphragm casing 37 is bowed or flared away from the section 32, 36. The head is provided with an annular groove 39 which fits snugly in an opening 40 of a valve actuating diaphragm 41, the periphery of which is clamped between the outer portion of the flange 36 and the pe ripheral portion of the casing section 38. by fastenings 42. Said fastenings 42 detachably secure said diaphragm casing section 38 to the housing 28 to form the diaphragm casing 37 in which the diaphragm 41 is movably disposed.

The outer diaphragm casing section 38' has an outwardly extending centrally disposed barrel portion 43' in which is threadedly received a spring tension adjusting screw 44 having a restricted inner end portion 45 which is spaced from a restricted outer end 46 of the head 35'.' An expansion coil spring 47 is disposed in the barrel 43 and has one. end extending into the diaphragm casing 37 and bearing against a spring seat 48 of the head 35 and" fitting around said extension 46. The other end of the spring 47 fitsloosely around: the extension 45 and bears against a shoulder 49 of the adjusting screw 44. A retaining nut 50 threadcdly engages the screw 44 and bears against the outer end of the barrel 43 to retain said screw in different adjusted positions to maintain a desired pres sure on the spring 47. The screw- 44 has a bore 51 extending longitudinally therethrough and is provided with a kcrf 52 in its outer end to receive a screw driver for turning said screw.

The valve 33 is provided with spaced bore portions 53, 54 and 55 of relatively large diameters. A restricted bore 56 is formed in the valve 33 between the forward end of the forward bore portion 53' and the concave forward end 34 of said valve and which forms a connecting passage between the passage 30 and the bore portion 53.

portion 54. A yieldable valve seat 58 is disposed in the rear end of the bore portion 53 around the forward end of the bore 57 and in which is normally seated an air pressure relief valve 59 having a stem 60 extending therefrom loosely through the bore 57 into the bore portion 54. An expansion spring 61 and a spring stop 62 are mounted on the stem 60 within the bore portion 54 for normally retaining the valve 59 in a closed position.

A restricted bore portion 63 connects the rear end of the bore portion 54 and the forward end of the bore portion 55 and said parts are provided with a vacuum release valve 64, corresponding to the valve 59 and which is spring retained in a closed position in the same manner as said valve 59. The rear end of the bore portion 55 opens into the diaphragm casing 37 beyond the diaphragm 41 and is in communication with the barrel 43 and accordingly with the bore 51.

The valve housing 28 has a nipple 65 projecting radially therefrom which is spaced from its ends. The outer end of the nipple 65 threadedly fits into an opening 66 in the diaphragm casing section 12. The nipple 65 has a bore 67 extending longitudinally therethrough, the outer end of which opens into an intermediate chamber 68 of the diaphragm casing 9, between the diaphragms 16 and 17 thereof. The other, inwardly flared end 69 of the bore 67 opens into an intermediate portion of the longitudinal bore 31 and communicates with the intermediate bore portion 54 through a radial port 70 in the valve 33. The housing 28 has a longitudinal passage or bore 71 the intermediate portion of which communicates with the flared bore portion 69. The forward end of the bore or passage 71 is turned inwardly and opens into the bore 31 adjacent the valve seat 29 and is normally closed by the forward portion of the valve 33. The rear end of the bore or passage 71 opens into the diaphragm casing 37 between the diaphragm 41 and the rear end of the valve housing 28.

The front diaphragm casing section is provided with an integral forwardly extending, centrally disposed barrel portion 72 having a bore 73 extending longitudinally therethrough the inner end of which opens into a front diaphragm chamber 74, formed by the main diaphragm 17 and the front casing section 10. A pair of plates 75 and 76 are clamped by fastenings 77 against opposite sides of the main diaphragm 17. The plate 76, which is disposed in the chamber 74, has an integral guide sleeve 78 projecting therefrom longitudinally through the bore 73 and to beyond the forward end of the barrel 72, as seen in Figure 3A. The barrel 72 is recessed around its bore 73 and longitudinally thereof to provide a seat 79 for one end of an expansion coil spring 80, the opposite end of which seats against the plate 76 and within a flange 81 of said plate, which forms a seat for the last mentioned end of the spring 80.

A pair of plates 82 and 83 are clamped to opposite sides of the central portion of the auxiliary diaphragm 16 by fastenings 84. The plate 83 which is disposed in the chamber 68 is provided with an integral sleeve 85 which pro ects perpendicularly therefrom. The sleeve 85 extends slidably through aligned openings 86 of the clamp plates 75 and 76 and extends slidably into the guide sleeve 78 A permanently lubricated ring 87 is seated in the guide sleeve 85 near its forward or outer end and slidably engages the wall of the bore of the guide sleeve 78 to provide a seal therebetween. The guide sleeve 85, ad acent the plate 83, is provided with a vent port 88 wh ch opens into the chamber 68. An expansion coil spring 89 has one end seated against the central portion of the clamp plate 83 and extends longitudinally through the guide sleeves 85 and 78 and has its opposite end seated against the closed forward or outer end of the guide sleeve 78, shown in Figure 3A and designated 90. A rod 91 forms a guide for the spring 89 and has one end thereof threadedly secured in the closed outer end 90 of the outer guide sleeve 78 and extends therefrom through the spring 89 into the outer portion of the inner sleeve 85.

The barrel 72, adjacent its outer end, is provided with a lubricating reservoir 92 a restricted inner end of which opens into the bore 73, for lubricating said bore and the guide sleeve 78. The reservoir 92 contains a wick 93 which is saturated with a lubricant of a tyne which will not be injurious to the dia hragm 17. The outer end of the reservoir 92 is closed by a removable plug 94. The casing sectlon 10 below the barrel 72 is provided with an internal upwardly opening groove 95 having at least one port 96 opening into the bed thereof and outwardly of said section 10. The groove 95 is provided to catch any of the lubricant from the reservoir 92 draining downwardly from the inner end of the barrel 72 and for discharging said lubricant externally of the casing 9 through the port 96. The port 96 also functions as a vent port for the chamber 74 to allow an unimpeded movement of the diaphragm 17. A threaded clean-out hole 97 is provided in the bottom of the intermediate casing section 12 which is normally closed by a removable plug 98, so that the casing chamber 68 may be cleaned. Likewise, a gauge may be applied to the port 97 for measuring the air pressure or vacuum therein.

A coupling block 99 is disposed beyond the outer end of the barrel 72 and is provided with a socket 100 to receive the outer end of the outer guide sleeve 78 which is detachably secured therein by setscrews 101. An annular resilient packing and sealing ring 102 is mounted in an annular groove 103 formed in the inner end of the block 99 and protrudes therefrom to normally bear against the outer end of the barrel 72 for sealing the space around the guide sleeve 78 between the barrel 72 and the connector block 99. The sealing ring 102 also functions as a shock absorber for the block 99 as it approaches the barrel 72. The opposite, outer end of the block 99 is provided with a hemispherical protuberance 104. The outer end of the block 99 is externally threaded as seen at 105 to receive a socket or sleeve nut 106 which is applied thereto by hand and without the use of a tool and which is retained in different adjusted positions by a setscrew 107, carried by the nut 106 and which bears against the block 99. A lubricant passage 108 is formed inthe block 99 and has one end opening outwardly of the protuberance 104 and its opposite end opening outwardly of the block 99, near the inner end of said block, and in which last mentioned end is mounted a conventional pressure grease fitting 109.

A push rod 110 extends loosely through a relative large opening 111 in the outer end of the nut 106. The inner end of the push rod 110 terminates in a socket 112 which engages the protuberance 104 and combines therewith to form a ball and socket joint. A tapered expansion coil spring 113 engages around the push rod 110, within the nut 106. The restricted end of the spring 113 bears against the socket 112 and the larger end thereof seats in a spring seat 114 formed in the nut 106 around the opening 111 thereof. The outer end of the push rod 110 is threaded to adjustably receive a shackle 115 which is retained in different adjusted positions thereon by a jamb nut 116. As illustrated in Figures 1 and 5, the shackle 115 is pivotally connected to the outer end of a lever arm 117 which is fixed to a brake shoe actuating shaft 118 which is journaled in a bearing 119. The bearing 119 may be fixed to the axle housing 14 or to one of the bracket arms 13. The shaft 118 extends into a wheel brake 120 for actuating the wheel brake to apply the brake shoes thereof, not shown, in a conventional manner, when the push rod 110 is displaced from left to right to turn the shaft 118 clockwise as seen in Figure 5. The ball and socket joint 104, 112 allows the necessary rocking movement of the push rod 110 to accommodate the arcuate swinging movement of the lever arm 117.

The outlet end of a flexible hose or conduit 121 is stretched over the nipple 24. Said hose 121 is connected to a suitable source of air under pressure. The control of air therethrough may be regulated by any conventional valve means operated with the hand or foot and a conventional quick release valve 122 may be interposed in the air supply line 121 for releasing the air under pressure to the atmosphere when desired. It will be understood that one of the units 8 would be associated with each vehicle wheel brake-where used in connection with the vehicle brakes and that air would be supplied simultaneously to each unit 8 and released simultaneously therefrom.

Assuming that it is desired to apply the vehicle brakes, compressed air is supplied to the inlet fitting 18 through the hose 121. A portion of the compressed air will enter the auxiliary diaphragm chamber 21 through the nipple 19 to initially displace the auxiliary diaphragm 16 toward the main diaphragm 17. The casing chamber 68 is thus restricted for producing an air pressure therein. A portion of the compressed air also moves through the conduits 23 and 26 into the passage 30 and into the forward end of the valve However, this air; pres-. sure actsin all directions on the walls of the bore portions 53 and 563V and does not unseat the valve. 33 from its seat 29-. However, the pressure generated in the cham-- ber 68 passes through the bore 67 into the bore 71 and impinges against the valve diaphragm 41 to displace said diaphragm from. left to, right against the spring 47. This movement of the valve diaphragm 41 causes the valve 33 to move from left to right uncovering the bore end 71 located adjacent the valve seat 29. While thisis occurring, the pressure in the chamber 68 causes the main diaphragm to. be displaced toward the casing section thereby causing the guide sleeve 78' and connecting block 95% to be moved from left to. right as seen in Figures 3 and 3A to cause the push rod 110 to move in the same direction to initiallycommence application of the brake shoes which are operated by the brake: shaft 118-, as previously described.

Assuming, for example, that the tension of the spring 47 has been adjusted by the screw 44 to require a pressure of twenty pounds per square inch to move the valve 33 to the right to expose the passage 71, as previously described, and that this pressure has been obtained, the air will then pass from the passage 30 through the passage 71 and bore 67 into the chamber 68. When this occurs, the air pressure on opposite sides of the auxiliary diaphragm 16 in the chambers 21 and 68 will be immediately equalized so that the spring 89, which is under tension, can expand and force the auxiliary diaphragm 16 back against the end casing section 11. Any additional air pressure thereafter applied will enter the chamber 68 through the multiple valve 28 to further displace the main diaphragm 17, guide sleeve 78 and push rod 110 from left to right of Figures 3 and 3A, against the action of the spring 80.

When the air pressure in the hose 121 is released in any conventional manner, not shown, the spring 80 will return the main diaphragm 17 to an inoperative position extended into the chamber 68 and away from the end casing section 10. Movement of the diaphragm 17 in either direction will cause air to pass either inwardly or outwardly through the port 96, so that movement of the main diaphragm will not be impeded by an air pressure or partial vacuum between the diaphragm and the end section 10. As the main diaphragm 17 is displaced by the spring 80 into the chamber 68, a portion of the air in said chamber will be forced therefrom through the bore 67 and passage 71 to the passage 30 until the pressure drops sutficiently to allow the spring 47 to return the valve diaphragm 41 and the valve 33 to their positions of Figures 3 and 4. When this occurs, the remaining pressure will be maintained in the chamber 68. Consequently, less air pressure will be required to again displace the push rod 110 to the right, as previ ously described, since the chamber 68 will already contain air under pressure when the auxiliary diaphragm 16 commences to move toward the main diaphragm 17, thereby elfecting a substantial saving in the amount of compressed air required to actuate the unit 8. Any slight excess of pressure within the chamber 68 after the valve 33 has closed will force the valve 59 open to allow escape of the air until a proper pressure exists in the chamber 68.

If a serious leak should occur in either the main diaphragm 17 or the valve diaphragm 41 while the unit 8 is being actuated and after the auxiliary diaphragm 16 has been returned to a position against the end casing section 11 but while the valve 33 is still open, the drop in pressure in the chamber 68 will enable the spring 47 to immediately close the valve 33 and the compressed air will. then act against the auxiliary diaphragm 16 forcing the plate 83 thereof against the plate 75 to thereby displace the main diaphragm 17 and the parts actuated thereby from left to right of Figures 3 and 3A to apply or maintain the brakes in an applied position.

Should a serious leak occur in the auxiliary diaphragm 16 while the unit 8 is being actuated, the spring 89 will return said diaphragm to a position against the end casing section 11 and the pressure in the chamber 68 will still cause the unit 8 to assume an operative position, as previously described, by movement of the main diaphragm 17 toward the end casing section 10.

Should leaks occur in both the auxiliary diaphragm 16 and the valve diaphragm 41 the unit 8 will still be rendered operative by the compressed air supplied 6 through the base. 121 since the restricted passage 51 will materially restrict the escape of air through the. diaphragm 41 1 By maintaining the unit 8 in anoperative position but withinsufiicient' compressed air being supplied thereto to open the valve 33,, even a slight leak in either the main diaphragm IT or; the valve diaphragm 41 will allow the auxiliary diaphragm 16 to move into engage ment' with the, main diaphragm 17 thereby setting. upa partial vacuum in thechamber 68. This will cause the relief valve 64 to opento admit air in the chamber 68 through, the passage 51, bores 55' and 63., port 70' and bore, 67.

As previously stated, the unit 8 may be employed for any purpose where a device can be operated by a mechanical thrust such as; is imparted by movement of the push rod from left to right of Figure 3A.

Various modifications and changes are contemplated and may obviously be resorted to, without departing from the spirit or scope of the invention as hereinafter defined by the appended claims.

I claim as my invention:

1. A pneumatic pressure responsive actuator comprising a diaphragm casing, an auxiliary diaphragm and a main diaphragm mounted in said casing and forming a main pressure chamber between said diaphragms and an auxiliary chamber between the auxiliary diaphragm and an adjacent end of the casing, a force imparting member conected to the main diaphragm and ex tending through the other second end of said casing, a compressed air supply conduit having a discharge end opening into said auxiliary chamber, said conduit having a bypass opening into the main pressure chamber whereby both of said chambers will be pressurized for displacing the diaphragms toward the last mentioned casing end for projecting said force imparting member outwardly of said second casing end, a valve unit interposed in said conduit bypass including a normally closed valve preventing the passage of air under pressure to or from said main pressure chamber, and means forming a part of said valve unit and responsive to the pressure in the main pressure chamber for opening said valve when the pressure in the main pressure chamber is increased by movement of the auxiliary diaphragm to ward the main diaphragm.

2. A pneumatic pressure responsive actuator as in claim 1, said valve unit providing a passage communicating with the atmosphere and opening into said main pressure chamber for relieving a vacuum or suction in said main pressure chamber, a portion of said passage being formed in said normally closed valve, and a normally closed relief valve mounted in said passage portion to open in response to a negative pressure in the main pressure chamber.

3. A pneumatic pressure responsive actuator as in claim 2, said first mentioned normally closed valve having a bore portion forming an auxiliary passage between said main pressure chamber and the bypass, and a normally closed pressure relief valve mounted in said last mentioned bore portion and arranged to open in response to an excessive pressure in the main pressure chamber for releasing the air therefrom to the bypass and conduit.

4. A pneumatic pressure responsive actuator as in claim 3, said valve actuating pressure responsive means comprising a diaphragm mounted in said valve unit and connected to said first mentioned normally closed valve, and spring means acting against said diaphragm to normally maintain said first mentioned normally closed valve in a closed position.

5. A pneumatic pressure responsive actuator as in claim 1, said second diaphragm casing end having an integral outwardly projecting barrel portion, said force imparting member including a sleeve extending slidably through and outwardly from said barrel portion, spring means extending between said barrel and the main diaphragm and urging the main diaphragm away from said second casing end, a guide member extending from and secured to the auxiliary diaphragm and projecting through the main diaphragm and slidably engaging in said sleeve, and a second spring means urging said guide member and auxiliary diaphragm toward said first mentioned casing end and away from the main diaphragm.

6. A pneumatic pressure responsive actuator as in claim 5, a push rod constituting an outer section of said force imparting member, and a coupling connecting said sleeve and push rod beyond the outer end of said barrel and forming a yieldable universal connection between the sleeve and push rod.

7. A pneumatic pressure responsive actuator com-.

prising a casing, a main diaphragm and an auxiliary diaphragm mounted in said casing and forming a main pressure chamber between the diaphragms and an auxiliary pressure chamber between the auxiliary diaphragm and a first end of the casing, force imparting means connected to the main diaphragm and extending therefrom slidably through a second end of the casing, a compressed air supply conduit opening into said auxiliary pressure chamber for displacing the auxiliary diaphragm toward the main diaphragm, a bypass conduit leading from said air pressure supply conduit and opening into the main pressure chamber, a first spring means urging the main diaphragm away from said second casing end, a second spring means urging the auxiliary diaphragm toward said first casing end, and a valve unit interposed in said bypass conduit including a normally closed valve and means connected thereto and responsive to the pressure in the main pressure chamber for opening said valve in response to an increase in pressure in the main chamber.

8. A pneumatic pressure responsive actuator as in claim 7, and means normally urging using valve to a closed position and for varying the amount of pressure in the main pressure chamber necessary to open said valve.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,575,937 Bent Nov. 20, 1951 2,649,169 Holman Aug. 18, 1953 

